Light-sensitive material

ABSTRACT

A light-sensitive material comprising a silver halide emulsion layer containing a mercury (II) oxide is described. The mercury (II) oxide stabilizes the emulsion against any increase in fog without substantial desensitization of the emulsion.

United States Patent Jozef Frans Willems Wilrijk; Robrecht Julius Thiers, Brasschaat; Bernard Hippoliet Tavernier, Edegem, all of Belgium 688,705 Dec. 7, 1967 Oct. 26, 1971 [73] Assignee Gevaert-AGFA,N.V.

Mortsel, Belgium [32] Priority Mar. 6, 1967 [33] Great Britain [31] 10,371/67 [72] Inventors [21 Appl. No. [22] Filed [45] Patented [54] LIGHT-SENSITIVE MATERIAL 9 Claims, No Drawings [52] U.S. Cl

[50] Field of Search 1. 96/109, 1 10, 108

[56] References Cited UNYT ED STATES PATENTS 2,728,664 12/1955 Carroll et a1 96/110 FOREIGN PATENTS 561,661 8/1958 Canada 96/109 Primary ExaminerMurray Katz Assistant Examiner-Raymond M. Speer Attorney-Alfred W. Breiner ABSTRACT: A light-sensitive material comprising a silver halide emulsion layer containing a mercury (11) oxide is described. The mercury (11) oxide stabilizes the emulsion against any increase in fog without substantial desensitization of the emulsion.

LIGHT-SENSITIVE MATERIAL This invention relates to improved light-sensitive silver halide emulsions.

Light-sensitive silver halide emulsions are in general characterized by their sensitivity, gradation and fog.

As is well known, sensitivity, gradation and fog are determined by the way in which the silver halide emulsion is prepared and by the use of special chemical ingredients effecting a desired improvement or result. Addenda to the emulsion which are of particular importance for the stability of the light-sensitive characteristics of the silver halide emulsion are the so-called stabilizers.

Stabilizers or antifoggants protect the light-sensitive silver halide emulsions against spontaneous formation and growth of fog known as chemical fog during prolonged storage at high temperatures and humidities or during development to maximum contrast and speed. Indeed, the fog increases with the degree and temperature of development, and in constant development circumstances with the time the light-sensitive emulsion is stored and with the temperature and the relative humidity of the atmosphere wherein the emulsion is stored. It is evident that a light-sensitive emulsion should be obtained which is as stable as possible at high temperature and high relative humidity for instance, in view of its use in tropical countries.

It is known to protect light-sensitive silver halide emulsions against the growth of chemical fog during storage by addition of stabilizers of the triazolopyrimidine type (azaindolizines). Heterocyclic thioxo and mercapto compounds too have been proposed for this purpose but show the disadvantage of impairing the sensitivity and gradation. The same disadvantageous influence on the sensitivity occurs with the simple inorganic mercury salts, addition complexes of mercury with amines, organic mercury salts and heterocyclic mercury compounds. Indeed these compounds when used in the concentration necessary for obtaining a sufficient antifogging action, have a considerable desensitizing effect.

It is also known that emulsions stabilized with compounds of the triazolopyrimidine type still show a tendency to fog formation in extreme storage circumstances i.e., at very high tem perature and humidity and in extreme development circumstances e.g., rapid processing at elevated temperature. The addition to these emulsions of the above known mercury compounds reduces the fogging tendency but, as mentioned above, at the cost of a reduction of the sensitivity.

It has now been found that the incorporation of mercury(ll) oxide into a light-sensitive material comprising at least one silver halide emulsion layer improves the stability thereof without presenting any increase of fog and does not cause a noteworthy desensitization thereof.

The mercury(ll) oxide of use according to the present invention is preferably incorporated into the silver halide emulsion from a dispersion in water which dispersion occasionally comprises dispersing agents and/or protective colloids in order to keep the dispersion stable.

The aqueous dispersion of mercury(ll) oxide can be prepared in many different ways. For instance, commercially available solid mercury(ll) oxide is ground in aqueous medium. This can be done in the presence of one or more dispersing agents and/or protective colloids according to known dispersion techniques e.g., by means of ultrasonic wave generators, colloid mills, sand mills, ball mills, homogenizers, high-speed stirrers, etc. Instead of using commercially available mercury(ll) oxide it is also possible to prepare said pigment e.g., by reaction of a water-soluble mercury(ll) salt e.g., mercury(ll) acetate, mercury(ll) chloride etc. with an excess of alkali such as potassium or sodium hydroxide whereupon the precipitate of mercury( ll) oxide is separated and dried at about 110 C. As an alternative, mercury(ll) oxide can be precipitated and dispersed in situ by treating an aqueous solution of a water-soluble mercury(ll) salt with alkali, preferably in the presence of dispersing agent(s) and/or protective colloid(s). The preparation of dispersions of mercury(ll) oxide preferably occurs under nonactinic lighting; as a matter of fact mercury(ll) oxide is light-sensitive and part of it could be reduced to metallic mercury particularly when in finely divided state. Although some detailed methods are given hereinafter, as illustrative of the preparation of dispersions of mercury(ll) oxide there can also be referred to German Patent 179,980, to J. Phys. Chem. 18 (l9l3- I914) 269-277and to Koll.Z. 18 (1916) 97-10] which references deal with the preparation of hydrosols, jellies, etc., of mercury(ll) oxide.

The protective colloids of use in the dispersion of mercury(ll) oxide are preferably of the nonreducing type. Examples of suitable protective colloids are: polyvinyl alcohol, poly-N- vinylpyrrolidone, carboxymethylcellulose, dextrin, sodium alginate, starch, gum arabic, etc.

All classical type surfactants may be used as dispersing agents in the preparations of the mercury(ll) oxide dispersion, for example soaps, sulfonated sulfated or carboxylated fatty alcohols, ammonium quaternary salts such as lauryl trimethylammonium chloride, alkylaryl sulfates and sulfonates, alkylnaphthalene sulfonates such as LOMAR D (trade name of Nopco Chemical Company, Newark, N..l., USA) esters of sodium sulphosuccinic acid such as the di(2- ethylhexyl) ester of sulphosuccinic acid sodium salt and AEROSOL 22 (trade name of American Cyanamid Co., New York, N.Y., USA) for the dispersing agent with formula:

CHr-COONa SOaNB H-COONB polymetaphosphates such as CALGON (trade name of Albright & Wilson Ltd., London, England), acid phosphoric acid esters such as ANTARA LM-700 (trade name of Antara Chemicals, a Division of General Aniline and FILM Corporation, New YORK, N.Y., U.S.A.) sulfonated castor oil, etc.

The following preparations illustrate more particularly how aqueous dispersions of mercury(ll) oxide can be prepared.

Preparation 1 3.2 g. (10 mole) of mercury(ll) acetate are dissolved in 100 ml. of water whereupon 100 ml. of a 1 percent aqueous solution of polyvinyl alcohol are added.

The solution is stirred thoroughly and mercury(ll) oxide is precipitated by addition of a small excess (about l0 percent) of lN sodium hydroxide. The precipitate is allowed to settle and the clear, supernatant liquid is removed by suction.

The precipitate is made alkali-free by washing four times with 100 ml. of a 1 percent polyvinyl alcohol solution, each time removing the supernatant clear solution by suction.

Flnally 400 ml. of a 1 percent aqueous solution of polyvinyl alcohol are added and the mercury(ll) oxide is redispersed therein by mechanical stirring.

Preparation 2 Preparation 1 is repeated with the difference however that the mercury(ll) oxide is redispersed in 200 ml. of a 1 percent aqueous solution of polyvinyl alcohol whereupon 200 ml. of a 10 percent aqueous gelatin solution is added.

Preparation 3 3.2 g. of mercury(ll) acetate are dissolved in 150 ml. of water comprising 1.5 g. of CALGON (trade name). To this solution, 22 ml. of N sodium hydroxide (an excess of about l0 percent) are added dropwise under continuous stirring. A yellow dispersion forms.

Preparation 4 2 g. of carboxymethylcellulose are added to 150 ml. of water while stirring. The liquid is allowed to swell by placing it in a water bath at C. Then 22 ml. of N sodium hydroxide are added with stirring whereupon a solution of 3.2 g. of mercury(ll) acetate in ml. of water is added dropwise. A yellow dispersion forms.

Preparation 5 Preparation 4 is repeated with the difference however, that 4 g. of sodium alginate is used instead of 2 g. of carboxymethylcellulose.

Preparation 6 6 g. of poly-N-vinylpyrrolidone are dissolved in 150 m1. of water with stirring whereupon a solution of 3.2 g. of mercury(ll) ace ate in 100 ml. of water is added. Then 22 ml. of N sodium hydroxide are added dropwise under thorough stirring. A yellow dispersion forms.

Preparation 7 2 g. of polyvinyl alcohol are dissolved in 300 ml. of water with stirring and heating at 80 C. To the solution obtained is added under stirring a solution of 3.2 g. of mercury(ll) acetate in 100 ml. of water. Then 22 ml. of N sodium hydroxide are added dropwise under thorough stirring. A yellow dispersion forms.

Preparations 8-12 3.2 g. of mercury(ll) acetate are dissolved in 150 ml. of water whereupon a solution in 100 ml. of water of 1 g. of one of the following products is added as dispersing agent or protective colloid:

a. LOMAR D (trade name) (preparationS);

b. Dextrin (preparation9);

c. Sulfonated castor oil (preparation 10);

d. AEROSOL 22 (trade nam (preparation 1 1).

To the solution obtained 22 ml. of N sodium hydroxide are added dropwise under thorough stirring. A yellow dispersion of mercury(ll) oxide is formed.

Preparation 13 2.175 g. of solid mercury(ll) oxide are added to 100 ml. of water comprising 1 g. of dextrin. The mixture is ground for 1 hour in a sand mill comprising 500 g. of sand at 36 C. The mixture is filtered and the volume of the filtrate is brought to 272 ml.

Preparation 14 3.2 g. of mercury(ll) acetate are dissolved in 150 ml. of water whereupon a solution in 100 ml. of water of 1 g. of dextrin and l g. of LOMAR D (trade name) is added.

To the solution obtained 22 ml. ofN sodium hydroxide are added dropwise under thorough stirring. A yellow dispersion of mercury( 11) oxide is formed.

Preparation 15 6.9 g. of mercury(ll) oxide, 10 g. of ATTAGEL 40 (registered trademark for a complex magnesium aluminum silica te for use as colloidal suspending, thickening and gelling agent providing thixotropic properties in aqueous systems marketed by Minerals & Chemicals Philipp Corporation, Menlo Park, NJ. USA), and 2.75 g. of LOMAR D (trade name) in 275 ml. of water are ground for hours in a ball mill. The ball mill has a contents of 1 liter and is filled with 300 ml. of porcelain balls having a diameter of 0.8 cm. A stable dispersion of mercury(ll) oxide is obtained comprising mg. ofmercury(ll) oxide per ml.

At the moment of addition to a silver halide emulsion 20 ml. of this dispersion can be diluted to form 1 liter with a suspension prepared by grinding in a ball mill 55.5 g. of ATTAGEL 40 (registered trademark), 1,500 ml. of water and 15 g. of LOMAR D (trade name).

- The mercury(ll) oxide of use according to the present invention can be incorporated into any type of light-sensitive silver halide emulsion, e.g., a spectrally sensitized or nonsensitized emulsion, an X-ray emulsion and an emulsion sensitive to infrared radiation. It may be incorporated into high speed negative emulsions as well as into rather low speed positive emulsions. Various silver salts may be used as light-sensitive salts, e.g., silver bromide, silver iodide, silver chloride, or mixed silver halides e.g., silver chlorobromide or silver bromoiodide.

The silver halides are dispersed in the common hydrophilic colloids such as gelatin, casein, zein, polyvinyl alcohol, car boxymethylcellulose, alginic acid, alginates, etc., gelatin, however, being favored.

The mercury(ll) oxide may be incorporated into the silver halide emulsion during no matter what step of emulsion preparation; however, it is preferably added to the emulsion after the chemical ripening and just before coating of the emulsion.

As compared with the known mercury compounds used as stabilizers, mercury(ll) oxide when used in the appropriate concentration does not cause or only to a slight extent a decrease in sensitivity. Consequently, mercury(ll) oxide is particularly suitable for use in combination with stabilizers of the hydroxytriazolopyrirnidine type (azaindolizines), especially in extreme storage and development circumstances. It can, of course, also be used in combination with other types of known stabilizers such as other mercury(ll) compounds and heterocyclic nitrogen containing thioxo compounds such as benzothiazoline-Z-thione and 1-phenyl-2-tetrazoline-5-thione. Mercury(ll) oxide of use according to the present invention is also particularly suitable for use in combination with compounds which sensitize the emulsion by development acceleration, for example compounds of the polyoxyalkylene type such as alkylene oxide condensation products as described among other in US. Pat. Nos. 2,531,832 and 2,533,990, in United Kingdom Pat. Nos. 920,637, 940,051, 945,340 and 991,608 and in Belgian Pat. No. 648,710, and onium derivatives of amino-N-oxides as described in United Kingdom Pat. application 42,592/65.

The amount of mercury(ll) oxide employed in the light-sensitive silver halide material depends on the particular type of material and the desired effect and can vary within very wide limits. The optimum amount of mercury(ll) oxide to be added can be determined for each particular type of material in a very simple way by application of the usual tests. Usually said compound is employed in a ratio of about 0.1 mg. to about 10 mg. per mole ofsilver halide.

The light-sensitive emulsions may be chemically as well as optically sensitized. They may be chemically sensitized by effecting the ripening in the presence of small amounts of sulfur containing compounds such as allyl thiocyanate, allylthiourea, sodium thiosulfate, etc. The emulsions may also be sensitized by means of reductors e.g., tin compounds as described in French Pat. No. 1,146,955 and in our Belgian Pat. No. 568,687, imino-aminomethane-sulfinic acid compounds as described in our United Kingdom Pat. No. 789,823 and small amounts of noble metal compounds such as of gold, platina, palladium, iridium, ruthenium and rhodium.

Other addenda such as hardening agents, wetting agents, plasticizers, color couplers, developing agents and optical sensitizers can be incorporated into the emulsion in the usual way.

The following examples illustrate the present invention.

EXAMPLE 1 A high-sensitive gelatino silver bromoiodide emulsion (:4,5 moles percent of iodide) is divided into 4 aliquot portions A, B, C and D.

To emulsion portion B are added per mole of silver halide 3 mg. of mercury(ll) cyanide, to emulsion portion C 1.5 mg. of mercury(ll) cyanide and to emulsion portion D 1.6 mg. of mercury(ll) oxide from a dispersion as described in preparation 1. To emulsion portion A no mercury compound is added.

The four emulsion portions are then coated on a cellulose triacetate support and dried whereupon the four materials thus obtained are stored for 5 days in an atmosphere of 57 C. and 34 percent of relative humidity.

The stored materials as well as 4 identical freshly prepared materials are exposed and developed for 5 minutes at 20 C. in a developing bath having the following composition:

water 800 ml. p-monomethylaminophenol sulfate 1.5 g sodium sulfite (anhydrous) 50 g hydroquinone 6 g sodium carbonate (anhyrous) 32 g potassium bromide 2 g. water up to 1,000 ml.

After the treatment in a stop bath, rinsing and fixing of the materials the following sensitometric results are obtained:

7 TABLE:

Freshly prepared materials Grada- Rel. speed tion (percent) Stored materials Gradetion Rel.

Material Fog speed EXAMPLE 2 A gelatino silver bromoiodide emulsion (0.20 mole percent of iodide) comprising per mole of silver halide 400 mg. of 5- methyl-7-hydroxy-s-triazolo-[l,5-a]-pyrimidine as stabilizer and per liter of emulsion l g. of saponin as coating aid, is divided into 3 aliquot portions.

To emulsion portions B and C are added per mole of silver halide 1 mg. of mercury(II) cyanide and 1.5 mg. of mercury(ll) oxide respectively from a dispersion as described in preparation 1. To emulsion portion A no mercury(II) compound is added.

The 3 emulsions are coated on a subbed cellulose triacetate support and the emulsion layers are then overcoated with a gelatin antistress layer.

The 3 materials A, B and C obtained are then stored for 36 hours in an atmosphere of 57 C. and 34 percent of relative humidity.

Thereupon the said 3 materials as well as 3 identical freshly prepared materials are exposed and developed for 4 minutes at 20 C. in a common X-ray developer having the following composition:

800 ml. 4g.

5 g. 1,000 ml.

water p-monomethylaminophenol hemisulfate hydroquinunc anhydrous sodium sulfitc anydrous sodium carbonate potassium bromide water up to The results attained are listed in the following table. 45

Stored materials Gradution Freshly prepared materials Grada- Rel. speed tion (percent) Rel. speed Material Fog EXAMPLE 3 The 9 materials obtained are developed for 8 minutes at 20 C. in the developing bath described in example 2.

The fog produced in the respective materials is listed in the following table.

Table Material Fog Dispersion of mercury l I oxide added A 0.27 none 13 0.13 dispersion of preparation 5 C 0.13 dispersion of preparation 6 D 0. l 4 dispersion of preparation 8 E 0.13 dispersion of preparation 9 F 0. l 4 dispersion of preparation l4 G 0. l 2 dispersion ofpreparation 10 H 0.l2 dispersion of preparation I l (M4 dispersion of preparation I We claim:

1. Photographic light-sensitive silver halide emulsion wherein mercury(II) oxide has been incorporated therein, said mercury(ll) oxide being incorporated from an aqueous dispersion comprising at least one protective colloid or dispersing agent and being present in an amount sufficient to stabilize said emulsion with regard to fogging.

2. Photographic light-sensitive emulsion according to claim 1, wherein said mercury(II) oxide has been incorporated in an amount varying from 0.1 to 10 mg. per mole of silver halide.

3. Photographic light-sensitive emulsion according to claim 1, wherein said mercury(ll) oxide has been incorporated from an aqueous dispersion comprising at least one protective colloid or dispersing agent.

4. Photographic light-sensitive emulsion according to claim 1, wherein said Protective colloid is selected from polyvinyl alcohol, poly-N-vinylpyrrolidone, sodium alginate, starch, dextrin, carboxymethylcellulose and gum arabic.

5. Photographic light-sensitive material comprising a support and at least one light-sensitive silver halide emulsion layer wherein an emulsion layer has been coated from a light-sensitive silver halide emulsion into which mercury(II) oxide has been incorporated, said mercury(II) oxide being incorporated from an aqueous dispersion comprising at least one protective colloid or dispersing agent and being present in an amount sufficient to stabilize said emulsion with regard to fogging.

6. Photographic light-sensitive material according to claim 5, wherein said material also comprises in an emulsion layer or in a colloid layer, in water-permeable relationship with said emulsion layer, a stabilizer of the hydroxytriazolopyrimidine type.

7. Photographic light-sensitive material according to claim 5, wherein said material also comprises in an emulsion layer or in a colloid layer, in water-permeable relationship with said emulsion layer a development accelerator of the polyoxyalkylene type.

8. A photographic light-sensitive material according to claim 5 wherein said protective colloid is selected from polyvinyl alcohol, poly-N-vinylpyrrolidone, sodium alginate, starch, dextrin, carboxymethylcellulose and gum arabic.

9. A photographic light-sensitive material according to claim 5, wherein the amount ofmercury(ll) oxide varies from 0.1 mg. to 10 mg. per mole of silver halide. 

2. Photographic light-sensitive emulsion according to claim 1, wherein said mercury(II) oxide has been incorporated in an amount varying from 0.1 to 10 mg. per mole of silver halide.
 3. Photographic light-sensitive emulsion according to claim 1, wherein said mercury(II) oxide has been incorporated from an aqueous dispersion comprising at least one protective colloid or dispersing agent.
 4. Photographic light-sensitive emulsion according to claim 1, wherein said protective colloid is selected from polyvinyl alcohol, poly-N-vinylpyrrolidone, sodium alginate, starch, dextrin, carboxymethylcellulose and gum arabic.
 5. Photographic light-sensitive material comprising a support and at least one light-sensitive silver halide emulsion layer wherein an emulsion layer has been coated from a light-sensitive silver halide emulsion into which mercury(II) oxide has been incorporated, said mercury(II) oxide being incorporated from an aqueous dispersion comprising at least one protective colloid or dispersing agent and being present in an amount sufficient to stabilize said emulsion with regard to fogging.
 6. Photographic light-sensitive material according to claim 5, wherein said material also comprises in an emulsion layer or in a colloid layer, in water-permeable relationship with said emulsion layer, a stabilizer of the hydroxytriazolopyrimidine type.
 7. Photographic light-sensitive material according to claim 5, wherein said material also comprises in an emulsion layer or in a colloid layer, in water-permeable relationship with said emulsion layer a development accelerator of the polyoxyalkylene type.
 8. A photographic light-sensitive material according to claim 5 wherein said protective colloid is selected from polyvinyl alcohol, poly-N-vinylpyrrolidone, sodium alginate, starch, dextrin, carboxymethylcellulose and gum arabic.
 9. A photographic light-sensitive material according to claim 5, wherein the amount of mercury(II) oxide varies from 0.1 mg. to 10 mg. per mole of silver halide. 